Electronic Conductivity Enhancement of (La, Sr)TiO3 with Nb‐Doping on B‐Site. Issue 6 (15th September 2014)

• Record Type: Journal Article
• Authors: Kazakevičius, E.; Tsekouras, G.; Michalow‐Mauke, K. A.; Kazlauskas, S.; Graule, T.
• Is Part Of: Fuel cells. Volume 14:Issue 6(2014:Dec.)
• Page Start: 954
• Page End: 960
• Publication Date: 2014-09-15
• Subjects: Fuel cells -- Periodicals; 621.312429
• DOI: 10.1002/fuce.201400015
• Languages: English
• ISSNs: 1615-6846

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>B‐site doped, A‐site deficient strontium titanates with general formula La<italic><sub>x</sub></italic>Sr<sub>1–3</sub><italic><sub>x</sub></italic><sub>/2+</sub><italic><sub>γx</sub></italic>Nb<italic><sub>y</sub></italic>Ti<sub>1–</sub><italic><sub>y</sub></italic>O<sub>3–<italic>δ</italic></sub> (<italic>x </italic>= 0.2, 0.25, 0.3, 0.35, 0.4; <italic>y </italic>= 0, 0.02, 0.03; <italic>γ </italic>= 0.03) were produced by flame spray synthesis and the electrical conductivity of dense ceramic bars sintered under reducing conditions measured over broad temperature and oxygen concentration ranges. As‐synthesized powders were nano‐scale and slightly reduced, while it was observed that sinterability was promoted by both La substitution and Nb doping. Electrical conductivity measurements on dense bars under reducing conditions revealed that stoichiometric substitution of Ti<sup>4+</sup> by Nb<sup>5+</sup> raised conductivity by ∼ 40%, with a maximum value of 226 S cm<sup>−1</sup> observed at 900 °C. This was attributed to a higher concentration of <inline-formula><alternatives><tex-math notation="tex"><![CDATA[$ {\rm{Ti}}_{{\rm{Ti}}}^{\prime} $]]></tex-math><inline-graphic xlink:href="ark:/27927/pgh2qsxbkj1" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></alternatives></inline-formula> defects, due to concurrent and enhanced oxygen vacancy (<inline-formula><alternatives><tex-math notation="tex"><![CDATA[$ {\rm{V}}_{\rm{o}}^{\bullet \bullet} $]]></tex-math><inline-graphic xlink:href="ark:/27927/pgh2qsxbkkk" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></alternatives></inline-formula>) formation under reducing conditions. The electronic properties of a slightly porous bar sample of the La<sub>0.3</sub>Sr<sub>0.559</sub>Nb<sub>0.02</sub>Ti<sub>0.98</sub>O<sub>3–<italic>δ</italic></sub> composition were found to be stable over one redox cycle.</p> </abstract>